I thought age 30 was typical college age in the RP canon?
30 is the typical age, but it seemed you were wanting to have her start early. So I was compromising and saying that she could have started college as early as 26. So in her bio, when you said she started college at 18, I was just suggesting she start at 26 instead. Nothing else about her bio needs to change.
30 is only a set in stone requirement for becoming a Pokemon Trainer.
Also, it's worth noting that college and education in general in this world would typically be harder and take more time to complete than in our world.